WO2016162088A1

WO2016162088A1 - Substrate holder and method for bonding two substrates

Info

Publication number: WO2016162088A1
Application number: PCT/EP2015/057859
Authority: WO
Inventors: Thomas Wagenleitner; Thomas PLACH; Jürgen Michael SÜSS; Jürgen MALLINGER
Original assignee: Ev Group E. Thallner Gmbh
Priority date: 2015-04-10
Filing date: 2015-04-10
Publication date: 2016-10-13
Also published as: SG11201706844QA; KR102298898B1; TWI647786B; TW201923962A; US11315813B2; KR20170137050A; TWI683393B; EP3281220A1; KR20200059324A; TW201642386A; CN107533996A; US20180040495A1; JP2018515908A; CN107533996B

Abstract

The invention relates to a substrate holder (1, 1', 1", 1'", 1^IV), comprising a fixing surface (4o) for holding a substrate (11, 11').

Description

Substrate holder and method for bonding two substrates

Description

The present invention relates to a substrate holder, a system comprising such a substrate holder, a use of such a substrate holder, a method for bonding two substrates and a product, in particular a substrate stack, produced by such a method and a use of such a substrate holder for such a method.

In the semiconductor industry substrates, especially wafers, with

different procedures aligned and interconnected. The process of bonding is called bonding. Depending on the too

Connecting materials require different bond technologies to achieve optimal results.

For example, metals are made by diffusion processes at high

Temperatures and high pressures are interconnected although in recent years, bonding techniques at room temperature have become more and more prevalent.

Substrates with surfaces whose atoms preferentially form covalent bonds are bonded together directly by adhesion forces. The Adhesion forces, however, do not increase the maximum bond strength between the surfaces, as it is initially only a van der Waals bond. By appropriate processes, in particular heat treatments, such van der Waals B indungen can be converted into covalent bonds. Bonding processes in which a connection of two surfaces through the

Formation of covalent compounds are referred to as fusion bonding processes. In recent years, it has become increasingly apparent that, above all, the maximization of the contact surface contributes significantly to the improvement of such a bond. This resulted in completely new possibilities for such surfaces even at room temperature, especially without

Heat treatment or to connect with only a very slight increase in temperature. Measurements have recently shown that by such

Optimization connection strengths of almost the theoretical strength of the materials to be joined together can be achieved.

In the case of fusion bonding, particular care must be taken to ensure that neither of the two substrates before and / or during and / or after alignment,

especially by thermal stress, uncontrollably stretches. An elongation leads to an enlargement or reduction of the substrate and thus to a displacement and / or misorientation of the features to be aligned, in particular chips, of the substrate. This shift and / or misorientation generally increases from the center to the edge. The result

The resulting error is in the prior art, but especially in the

Semiconductor industry, known as run-out. The compensation of the error is called run-out compensation. This error will be explained in more detail below.

One of the biggest technical problems of permanently bonding two substrates is the alignment accuracy of the functional units between the individual substrates. Although the substrates are aligned by alignment devices can be aligned very closely to each other, it can come during the bonding process itself to distortions of the substrates. Due to the resulting distortions, the functional units do not

necessarily be aligned correctly at all positions to each other. The alignment inaccuracy at a particular point on the substrate may be a result of distortion, scaling error, lens aberration

(Enlargement or reduction error), etc. In the semiconductor industry, all topics that address such issues are subsumed under the term "overlay." An introduction to this topic can be found, for example, in: Mack, Chris, Fundamental Principles of Optical Lithography, The Science of Microfabrication, Wiley, 2007 , Reprint 2012.

Each functional unit is designed in the computer before the actual manufacturing process. For example, patterns, microchips, MEMS, or any other microstructure fabricatable structure are designed in a computer aided design (CAD) program. However, during the fabrication of the functional units, it can be seen that there is always a divergence between the ideal, computer-designed, and the real, functional units produced in the clean room. The differences are mainly due to hardware limitations, ie engineering problems, but very often due to physical limitations. Thus, the resolution accuracy of a structure made by a photolithographic process is limited by the size of the apertures of the photomask and the wavelength of the light used. Mask distortions are transmitted directly into the photoresist.

Machine linear motors can only approach reproducible positions within a given tolerance, etc. It is therefore not surprising that the functional units of a substrate can not exactly match the structures constructed on the computer. All substrates therefore already have before

Bonding process a non-negligible deviation from the ideal state. If one now compares the positions and / or shapes of two opposite functional units of two substrates assuming that neither of the two substrates is distorted by a bonding process, then one notes that in general an imperfect coverage of the functional units already exists by the above-described mistakes of the ideal

Differ computer model. The most common errors are shown in FIG. 8

{Emulated by: http: //com.mons. wikimedia.org/wiki/File: Overlay _- _typical_model_terms DE.svg, 24.05.2013 and Mack, Chris. Fundamental

Principles of Optical Lithography - The Science of Microfabrication. Chichester: Wiley, p. 312, 2007, Reprint 2012). As shown in the figures, we can roughly distinguish between global and local or symmetric and asymmetric overlay errors. A global overlay error is homogeneous, therefore independent of location. He generates the same deviation between two

opposite functional units regardless of position. The classical global overlay errors are the errors I. and IL type, which result from a translation or rotation of the two substrates to each other. The translation or rotation of the two substrates generates a corresponding translational or rotational error for all, respectively opposite, functional units on the substrates. A local overlay error arises location-dependent, mainly by elasticity and / or plasticity problems, in the present case mainly caused by the continuous

spreading bond wave. Of the illustrated overlay errors, especially the errors III. and IV., referred to as a "run-out error." This error is primarily due to a distortion of at least one substrate during one

Bonding process. Due to the distortion of at least one substrate, the functional units of the first substrate with respect to the functional

Units of the second substrate are distorted. However, the errors I. and II. Can also arise through a bonding process, but are from the mistakes III- and IV. Mostly superimposed so heavily that they are difficult to identify or

are measurable.

The biggest problem with the approach of two substrates is that the environment is generally not in thermodynamic equilibrium with the substrates. A thermodynamic equilibrium is always present when all the intense thermodynamic quantities, in particular the temperature in the specific case, are the same for all the subsystems to be considered. In many cases, it is such that one of the substrates, in particular the substrate, which is fixed to the lower substrate holder, has an elevated temperature.

In many cases, it is desirable or even intended to set a different, especially higher, temperature for the lower substrate than is present at the upper substrate in order to compensate for the already mentioned run-out defects of the substrates in a controlled manner. It may be necessary to appropriately temper the lower substrate, in particular to heat or cool.

If the first, upper substrate, which is fixed on the substrate holder according to the invention, now approaches the second, lower substrate, then the second, lower substrate, but in particular also the entire lower substrate holder, can heat the upper, first substrate, thermally stretch and above all, expose a very complicated heating profile. The heating profile is determined by a temperature-time profile. In this case, even a very small temperature difference between the first and second substrate to a

significant stretching of the upper, first substrate lead or can heat the upper, first substrate according to a complicated temperature profile. The temperature of the upper substrate increases with decreasing distance between both substrates and remains constant for a short time in a saturation region, before it decreases by another process, in particular exponentially and then remains constant under unchanged boundary conditions. The state of the art has the particular problem that the substrates are bonded together in temperature ranges in which the temperature changes as a function of time. Thus, the bond wave is subject to different times, or in other words, different positions, different temperatures and thus produces the above-mentioned run-out errors.

It is therefore the object of the present invention to eliminate the disadvantages of the prior art and in particular to disclose an improved substrate holder and an improved method by means of which the run-out error

compensated, in particular, completely avoided, can be.

This object is achieved with the substrate holder according to the invention, the

Inventive plant, the use according to the invention, the

inventive method and the product according to the invention and the use according to the invention according to the independent claims.

Advantageous developments of the invention are in the dependent claims

specified. All combinations of at least two features specified in the description, in the claims and / or the drawings also fall within the scope of the invention. For specified value ranges, values lying within the stated limits should also be disclosed as limit values and may be claimed in any combination.

The core of the invention consists in particular of the invention, in particular upper (hereinafter also referred to as the first substrate holder),

Substrate holder to be constructed so that any recorded heat controlled, in particular on the back of the substrate holder, dissipated and discharged there via a heat exchanger, so that heating of the fixed, in particular upper (hereinafter also called first substrate), substrate can be selectively adjusted. Another important aspect of the invention is the targeted optimization of the thermal resistances of the system, in order to enable a targeted adjustment of the temperature difference ΔΤ according to the invention.

It is in particular an important aspect of the invention to set a desired temperature difference ΔΤ between the lower and the upper substrate by the suitable choice of thermal resistances. This temperature difference ΔΤ is generally a function of the time or distance between the two substrates. Of relevance according to the invention, however, is predominantly the temperature difference ΔΤ in the temperature range of the temperature saturation of the lower substrate, this temperature range being designated d in the further course of the patent. In this temperature range d, the temperature difference ΔΤ should be kept constant. Through the targeted adjustment and maintenance of the temperature difference ΔΤ, the disadvantageous "run-out" error can be reduced or even completely eliminated.

The temperature difference ΔΤ, in particular in the temperature saturation region d, is therefore generally (i) determined by the thermal resistances and / or (ii)

Heating elements, in particular a heater in the lower substrate holder, and / or (iii) by cooling elements, in particular a cooling fluid, specifically set.

According to the invention, the substrate holder has a fixing surface for holding a substrate, wherein the substrate holder has a heat conduction body for dissipating heat away from the fixing surface, preferably and / or for supplying heat to the fixing surface.

Another object of the present invention relates to a system for bonding a first substrate to a second substrate, comprising at least a substrate holder according to one of the preceding embodiments for supporting at least one of the two substrates. Reference is made in particular to the comments on the substrate holder.

Another object of the present invention relates to a use of a substrate holder according to the invention as the upper substrate holder.

Another, particularly independent, subject of the present invention relates to a method for bonding a first substrate to a second substrate, wherein the substrates are brought closer to each other in a first step, so that the temperature of the first substrate increases, wherein in a second step, the approach the substrates are stopped and the distance between the substrates is kept constant so that a constant temperature of the first substrate adjusts at a constant distance for at least a period of time, wherein in a third step within the period of time at a constant temperature of the first substrate, the two substrates, at least temporarily, be bonded together.

This fact can also be described in such a way that in the well-defined temperature range d the temperature difference ΔΤ between the two substrates is constant. By the correct choice of thermal resistances is

In addition, the size of the temperature difference .DELTA.Τ adjustable.

Another object of the present invention relates to a product,

in particular a substrate stack, comprising a first substrate and a second substrate, wherein the substrates are bonded together by a method according to the invention. Another object of the present invention relates to a use of such a substrate holder for holding a substrate during such a process.

In general, the substrate holder, especially the upper one, should be thermally coupled as well as possible to the ambient temperature. This can lead to an increase and / or dissipation of heat. As a result of the approach of the two substrates, in particular the upper substrate is heated by the lower substrate or the lower substrate holder. The large thermal mass of, in particular upper, substrate holder, as well as its highest possible thermal conductivity, dissipates the heat from, in particular upper, substrate. The inventive

Substrate holder is in particular designed so that its temperature profile, in particular the temperature profile of the upper substrate, can be adjusted specifically when approaching the lower substrate or the lower substrate holder.

The thermal resistances of the substrate holder according to the invention are in particular designed so that a temperature equalization of

Heat conduction body and thus the upper substrate to the cooling fluid as quickly and efficiently. The thermal resistances are therefore preferably minimized. The cooling fluid is preferably the ambient atmosphere. The temperature of the cooling fluid is therefore preferably the

Room temperature.

Through the knowledge of the temperature-time curve iixi, in particular upper,

Substrate holder or on, in particular upper, substrate can be determined in particular the optimum time for bonding, which is accompanied by an increase in throughput at the same time. The corresponding process or respectively

appropriate procedure also constitutes an important, in particular

independent, inventive aspect of the invention. All disclosed in the patent temperature profiles can as

Temperature profiles of a substrate on a substrate conductor or as

Temperature profiles of the substrate holder are considered. The thermal

Coupling of the substrates to the substrate holder is preferably so efficient that the deviation of the temperature is negligible. In reality, the temperature of the lower substrate with a heating lower substrate holder may be slightly lower than the temperature of the lower substrate holder. The

Temperature of the upper substrate is generally slightly higher than that

Temperature of the upper substrate holder according to the invention. The easy

Temperature difference has with the, from zero different, thermal

Resistances between the substrate holders and the substrates to do.

As already mentioned above, the substrate holder according to the invention, also referred to below as the sample holder, leads a possible amount of heat in a controlled manner to the rear side, where it is converted by a heat exchanger and removed by the substrate holder according to the invention. Furthermore, the large thermal mass of the, in particular upper, substrate holder ensures a

Temperature stabilization of, in particular upper, substrate, so that thermal fluctuations of the immediate environment are minimized as far as possible. It is another important aspect of the invention that the comparatively large thermal mass is the temperature of the upper substrate or the

Temperature difference ΔΤ stabilized between the lower and the upper substrate during the bonding process.

Furthermore, it is possible by the knowledge of heat dissipation by the substrate holder according to the invention to determine the temperature-time diagram for the, in particular upper substrate holder and the upper substrate, and, by changing the parameters of the substrate holder according to the invention allows to modify this. The substrate holder according to the invention can be used as upper and / or lower substrate holder. The substrate holder according to the invention is designed, in particular, as an upper substrate holder, so that the upper, first substrate fixed on it is deformed in the direction of gravity, as long as it is not fixed, in particular over its entire surface.

In the following, the roughness of a surface is referred to several times. Roughness is reported in the literature as either average roughness, square roughness or average roughness. The values determined for the average roughness, the square roughness and the average roughness

generally differ for the same measuring section or measuring surface, but are in the same order of magnitude. Therefore, the following are

Roughness numerical ranges are to be understood as either average roughness, squared roughness, or averaged roughness.

The substrate holder according to the invention is capable of heating and / or cooling the particular upper, first, substrate. Heat can be dissipated from the, in particular upper, first, substrate via the heat conduction body and can preferably be passed on to a cooling fluid. In this case, the heat conduction body would be a heat sink. It would also be conceivable, however, for the fluid to be a heating fluid which gives off heat to the heat conduction body and thus heats the upper, first substrate. In this case, the heat conduction body would be a heating body.

The cooling fluid is preferably the atmosphere of

Surroundings. The temperature of the cooling fluid is preferably the room temperature.

In a preferred embodiment it is provided that the

Heat conduction body, in particular facing away from the fixing surface Side (hereinafter also called the back), ribs for the removal and / or supply of heat. The ribs may in particular be arranged on the entire rear side of the heat conduction body, whereby an improved heat exchange can be made possible.

Through the ribs, heat can be distributed along a larger surface called a ribbed surface. The ribs may in particular be arranged perpendicular to the fixing surface. The ribs are preferably arranged parallel to one another. In the case of using a heat conduction body, as

Heat sink is used, it would be cooling fins. In the case of using a heat conduction body which serves as a heating body, one could refer to the ribs as heating ribs, which conduct the heat from the fluid optimally in the heat conduction body. In the further course, only ribs are spoken. As far as predominantly in the further course, unless explicitly mentioned, is spoken of cooling, the heat conduction body as a heat sink, the ribs are considered as cooling fins and the fluid as a cooling fluid.

The embodiments of the substrate holder according to the invention are preferably designed such that the ribs are located in an encapsulation, for example an enclosure. The encapsulation preferably has at least two accesses. One of the entrances is used to supply the fluid, the second of the discharge. This makes it possible to flow the fluid continuously and above all spatially separated from the environment via the ribs of the heat conduction body. Such a compact design also allows the separation of the embodiment of the invention from the surrounding components. If the cooling is gas cooling, in particular cooling with air, an inflow of the fins through a gas flow, in particular an air flow, via a blower may already be sufficient to ensure efficient cooling. In a very particularly preferred embodiment, the cooling fins are cooled only by the surrounding atmosphere. The flow rate of the fluid is preferably controllable. The flow rate is greater than l mm / s, preferably greater than lem / s, more preferably greater than 10cm / s, most preferably greater than 1 m / s. By a compact encapsulation, the fluid can also be pressurized. The pressure of the fluid preferably corresponds to the

Ambient pressure. The fluid can also be used under pressure. Then the pressure is greater than 1 bar, preferably greater than 2 bar, more preferably greater than 5 bar, most preferably greater than 10 bar, on

most preferred greater than 20 bar. The supply of the fluid in the

Encapsulation and thus to the ribs is preferably about

Hose systems connected to the accesses.

Optional cooling and heating elements

The substrate holder according to the invention, in addition to the, discussed below, the heat conduction body and the heat exchanger on its back over

have additional actively controllable cooling and / or heating elements. These additional cooling and / or heating elements are preferably in the

Inventive substrate holder, in particular in the heat conduction body, installed. It would also be conceivable to attach the cooling and / or heating elements to the periphery of the heat conduction body in order to leave the heat conduction body as homogeneous as possible and not to generate thermal impurities by additionally installed components.

A heating element is preferably an induction heater. As the temperature compensation, however, only for relatively smaller

Temperature differences must be made, it would also be conceivable to install infrared sources on the side of the heat conduction body, which can be controlled more accurate, faster and more efficient and the temperature of the Heat conduction body in the range of a few degrees Celsius through

Can increase radiant heat.

A cooling element could be additionally installed Peltier elements that are independent of the actual invention

Wärmeleitungskörper, an additional cooling of the invention

Allow substrate holder, in particular the heat conduction body. The

Peltier elements are preferably outside of the heat conduction body

attached in order not to destroy the material homogeneity of the heat conduction body.

The actual inventive aspect of the invention provides the

Heat conduction body.

The heat conduction body

The heat conduction body is a component with the largest possible thermal mass. The thermal mass is the product of the specific heat capacity and the mass of the body. With a constant density distribution, the mass can be replaced by the product of density and volume.

C = m * c = ö * V * c

The term thermal mass is used predominantly in engineering. In the natural sciences, one mainly uses the more common concept of heat capacity. The unit of heat capacity is J / K. It is a measure of a body's ability to heat at a certain level

To store temperature. Are bodies with a high heat capacity

Heat storage, which can serve as a buffer element. A temperature gradient generally drops above the heat conduction body when the temperature Tk of the cooling fluid used differs from the temperature of the upper substrate. Instead of the temperature gradient, an average temperature can also be considered. The temperature gradient or the

averaged temperature will be referred to as Tw in the further course of the patent. The temperature of the cooling fluid is preferably kept constant during the process according to the invention, while the temperature gradient or the average temperature Tw changes generally. The temperature Tw preferably always corresponds to the temperature of the upper substrate and deviates from this only marginally.

It is an important finding according to the invention that the temperature of the upper substrate, and of the inventive heat conduction body or of the entire upper substrate holder according to the invention, would correspond to the temperature of the cooling fluid, in particular the ambient temperature, provided that the thermal resistance Rth4 between the two substrates is infinite would be great. By a finite value of the thermal resistance Rth4, however, a heat flow from the lower substrate to the upper substrate is possible.

Erfindungsgeraäß is of particular importance that the temperature difference ΔΤ, especially during the temperature interval d, known and, above all, is selectively adjustable in order to reduce the run-out error or preferably completely eliminate it.

Since it is an object of the invention according to the invention to dissipate the temperature as controlled as possible on the substrate, but also to stabilize it correspondingly strong, the heat conduction body has a

highest possible heat capacity. The Wärmekapizität the heat conduction body is as large as possible in order to allow efficient storage of heat or

compensate for thermal fluctuations as efficiently as possible. The Temperature stability is also reflected in the stability of the temperature difference ΔΤ. Most solids differ in moderate ones

Temperatures and pressures, the heat capacity at constant volume only marginally from the heat capacity at constant pressure. In the further course, therefore, no distinction is made between the two heat capacities. Furthermore, specific heat capacities are specified. The specific heat capacity of the heat conduction body is in particular greater than 0.1 kJ / (kg * K), preferably greater than 0.5 kJ / (kg * K), more preferably greater than 1 kJ / (kg * K), on

most preferably greater than 10 kJ / (kg * K), most preferably greater than 20 kJ / (kg * K). The specific heat capacities can be converted into the absolute heat capacities by the above formulas with known density and geometry of the heat conduction body.

Since the heat must be removed as quickly as possible, that should

Heat conduction body material have the highest possible thermal conductivity. The thermal conductivity is between 0.1 W / (m * K) and 5000 W / (m * K), preferably between 1 W / (m * K) and 2500 W / (m * K), more preferably between 10 W / (m * K) and 1000 W / (m * K), most preferably between 100 W / (m * K) and 450 W / (m * K). For example, copper, the most widely used construction material for dissipating heat, has a thermal conductivity of about 400 W / (m * K). The thermal conductivity determines how much energy is transported per unit of time over a distance at a given temperature difference. The transported energy or heat quantity per unit of time is called the heat flow. The heat flux is greater than 1 J / s, preferably greater than 10 J / s, more preferably greater than 100 J / s, most preferably greater than 200 J / s, most preferably greater than 500 J / s.

The heat conduction body is preferably actively or passively cooled at its rear side. A passive cooling takes place by radiation of the heat, in particular by a possible large surface. The active cooling takes place via a Cooling fluid. The cooling fluid may be a gas or a liquid. For example, it would be conceivable

• Liquids, in particular

o water

o oils

• Gases, in particular

o noble gases

^■ helium

^■ Argon

o Molecular gases

^■ HCFC

"HFC

^■ CFC

^■ PFKW

* C02

- N2

- 02

• Gas mixtures, in particular

o air, in particular

^■ ambient ^air

The cooling fluids absorb the heat via the heat conduction body, are thereby heated and at the same time cool the heat conduction body. The heated cooling fluid is preferably circulated in a cooling circuit and releases the heat at another point of the circulatory system, is thereby cooled again and supplied to the cooling circuit again. Preferably, cooling gases are used because they are easier to handle. Is it the cooling fluid to the

Ambient air, the cooling is done by the release of heat from

Heat transfer body in the ambient air. The locally heated ambient air then distributes itself in the surrounding atmosphere and thus leads to a temperature equalization and cooling.

The distribution of heat over a larger surface increases the efficiency of the radiation or the heat transfer to the cooling fluid. The surface can be further increased by deliberately increasing the roughness of the surface. The roughness is greater than 10 nm, preferably greater than 100 nm, more preferably greater than 1 μιη, most preferably greater than 10 μηι, most preferably greater than 100 μηι.

It is also conceivable to use a heat conduction body without ribs, whereby the production of the heat conduction body can be simplified.

In a further embodiment according to the invention, it would be conceivable to provide at least the upper side of the heat conduction body with an open porosity. The pore size should be greater than 100 nm, preferably greater than 1 μιη, more preferably greater than 10 μιη, most preferably greater than 100 μπι, most preferably be around 1 mm. The cooling fluid flows through the open porosity and, due to the large surface area, absorbs the heat even more efficiently. It would also be conceivable to provide only the ribs with an open porosity to further increase the surface of the ribs.

The main object of the substrate holder according to the invention, in particular the

Wärmeleitungskörpers, consists in the temperature setting and

Temperature stabilization of the substrate or the temperature difference adjustment and temperature difference stabilization between the lower and the upper substrate. The substrate holder according to the invention leads the substrate to heat and / or dissipates heat, depending on whether the substrate is to be cooled and / or heated. The substrate holder according to the invention allows in particular the targeted setting of a maximum temperature or the temperature difference ΔΤ between the upper and the lower substrate and guarantees the

Temperature stability of the maximum temperature or the temperature difference .DELTA.Τ for a period of time, in particular equal to, even more preferably greater than the time required for bonding of the two substrates.

In the further section several embodiments of the invention are called, which differ from each other by at least one feature. All mentioned embodiments according to the invention are arbitrary and can be combined with one another in such a way that corresponding further embodiments according to the invention can be produced, which combine a number of said features.

In an exemplary embodiment of the invention, the

Inventive substrate holder a separate fixing part on which the

Heat transfer body is placed. Heat-conducting body and fixing part are therefore two different but interconnected components. The most efficient thermal Ankoppiung both components is done by flat as possible surfaces. The roughness of the mutually contacting surfaces of the fixing part or the heat conduction body is less than 100 μηι, preferably less than 10 μιη, more preferably less than 1 pm, on

most preferably less than 1 ÖOnm, most preferably less than 10nm. Further improvement of the thermal transition can be achieved by the use of thermal conductive pastes.

In another preferred embodiment, the fixing surface is formed integrally with the heat conduction body. In other words: the

Heat-conducting body itself is designed as a fixing part. The heat conduction body and the fixing part or the fixing surface are made in one piece. The substrate holder may have other components, but not further treated, shown or described, since they have the functionality of

Do not decisively influence the invention. By this invention Embodiment is an improved heat conduction possible because no

Interfaces between the fixing part and heat-conducting body are present.

Since the embodiment of the one-piece heat conduction body according to the invention is the optimum embodiment according to the invention, all variations will be referred to hereinafter to this basic type. Fixing part and heat conduction body are therefore used synonymously in the remainder of the text.

In another particularly preferred embodiment according to the invention, the substrate holder has at least one, in particular movable, preferably drivable, deformation element for deforming the substrate, the at least one deformation element preferably being centered in the substrate holder

is arranged. The at least one deformation element can in particular be movable perpendicular to the fixing surface or to the fixed substrate,

be drivable in particular. The at least one deformation element is preferably designed such that the substrate is deformable away from the fixing surface. The substrate holder or heat conduction body may be a,

in particular centrically applied and / or continuously extending, bore, in which the at least one deformation element, in particular movable, preferably driven, is arranged, or which allows the access of the at least one deformation element, with which the fixed substrate can be deformed. The at least one deformation element is for example

A pen

A thorn

A ball

A nozzle, in particular

o A gas nozzle The deformation element is operated or controlled in such a way that it is capable of deforming the substrate, at least locally, preferably in the middle, by targeted activation. The deformation is there, from the side of the

Considering deformation element, preferably concave. The deformation serves in particular for the detachment process of the substrate from the fixing part or from the fixing surface.

In a further embodiment of the invention, has the

Heat conduction body in the fixing surface at least one recess and / or recess to ensure the lowest possible contact of the substrate to the fixing surface or to the material of the heat conduction body. As a result, the so-called effective fixing surface is reduced. The effective fixation surface is that portion of the fixation surface that is actually in contact with the substrate. Preferably, at least one recess is arranged in the fixing surface, so that the substrate from the fixing surface

spaced durable. The advantage of this embodiment according to the invention is that impurities of the substrate are reduced by the surface of the heat conduction body. In order to carry out the heat transfer efficiently, a gas having a correspondingly high thermal conductivity and correspondingly high heat capacity can be introduced into the at least one recess and / or depression, in particular, flowed through. The substrate is then fixed only to a few, in particular at the periphery and / or in the center, fixing elements. Such an embodiment is disclosed in the publication WO2013 / 0237G8A1, the disclosure content of which is expressly incorporated in the disclosure content of this application with respect to this embodiment.

In a further embodiment according to the invention, nub-shaped (nubs) and / or needle-shaped and / or podium-shaped elements are arranged in the at least one depression, so that the substrate passes through these elements spaced apart from the fixing surface, which in particular can taper pointedly in the direction of the substrate. The elements reach to the

Surface of the heat conduction body and support the fixed substrate. In order to ensure the heat coupling between the fixed substrate and the heat conduction body, is also in this embodiment of the invention a

Flushing the spaces between the knobs and / or needles and / or pedestal with a fluid high heat capacity possible.

fixing

All disclosed embodiments of the invention are capable of fixing a substrate, in particular a wafer, more preferably a semiconductor wafer. The fixation can be done by any fixing. Preferably, in particular over the whole area, fixing elements for fixing the substrate are arranged in, on and / or on the fixing surface. It would be conceivable

vacuum fixations

Electrostatic fixations

Magnetic fixations

Mechanical fixations, in particular

o clamps

Adhesion fixations, in particular

o Fixations by adhesive films

Particularly preferred are, in particular distributed over the entire surface over the fixing surface, arranged vacuum fixings or vacuum webs (also referred to below as vacuum channels). The vacuum fixation consists of several

Vacuum channels, which in vacuum openings on the fixing of the

Substrate holder end. In another embodiment of the invention, the vacuum channels are connected to each other, so that an evacuation and / or flushing of

Vacuum channels can be done simultaneously.

In another embodiment of the invention at least individual vacuum channels are connected to each other and form corresponding

Vacuum channel groups. Each vacuum channel group can be customized

be controlled so that a piecewise fixation and / or release of the

Substrate can be achieved. In particular inventive

Embodiments, multiple vacuum ports are arranged in a plurality of centered, radius-differing, circles to a vacuum channel group. Advantageously, all vacuum channels of the same circuit are controlled simultaneously, so that the fixation and / or detachment of the substrate can begin centrally and can be steered progressively radially symmetrically outward. This results in a particularly efficient way of controlled

Fixation and / or detachment of the substrate.

Thermal resistance: equivalent circuit diagram

Another important inventive aspect of the invention is

in particular in an optimization of the heat flow through the

Substrate holder according to the invention. The heat flow between the heat source and the heat sink is decisively influenced by the thermal resistances. Any statistical many-particle system, hence fluids such as gases and liquids, as well as solids, has a thermal resistance. The definition of the thermal resistance is known to the person skilled in the art. The thermal resistance is not a pure material parameter. It depends on the thermal conductivity, the thickness and the cross section. In the further course of the document, it is assumed that the heat flow always flows through the same cross section, so that the thermal resistance, with a constant cross section, is to be regarded as a function of the thermal conductivity and the thickness of the respective considered material. The thermal resistance is abbreviated in the figures by Rth and an index.

According to the invention there are in particular eight relevant thermal resistances. Rth1 to Rth8 are the thermal resistances of the (i) lower substrate holder, (ii) the fluid or vacuum between the lower substrate holder and the lower substrate, (iii) the lower substrate, (iv) the fluid or vacuum between the two substrates, ( v) the upper substrate, (vi) the fluid or vacuum between the upper substrate and the upper substrate holder, (vü) the heat conduction body and (vni) the fluid flowing in particular between the cooling fins.

The heat flow is directly proportional to the applied temperature difference between the heat source and the heat sink. The thermal resistance is the proportionality constant. It therefore applies

ΔΓ dt

It is particularly another important aspect of the invention

Invention to minimize the thermal resistances above and / or below the substrates and to maximize the thermal resistance between the substrates. According to the invention, therefore, the thermal resistances

in particular as follows:

Rthl is minimized, especially by choosing a material with high thermal conductivity,

Rth2 is minimized, in particular by the choice of a fluid with high thermal conductivity,

- Rth3 should by choosing a substrate with a high thermal

Conductivity is minimized Rth4 is maximized, in particular by the flushing with a gas of low thermal conductivity and / or a vacuum and / or by an optimized process control, in particular by a skilful choice of the distance,

- Rth5 should by choosing a substrate with a high thermal

Conductivity is minimized

Rth6 is minimized, in particular by the choice of a fluid with high thermal conductivity,

Rth7 is minimized, in particular by the choice of a material with high thermal conductivity and / or

Rth8 is minimized, especially by choosing a fluid with high thermal conductivity.

In particular, it is an important aspect of the embodiment according to the invention to be able to set the temperature of the upper substrate or the temperature difference ΔΤ between the lower substrate and the upper substrate in a targeted manner and to keep them as constant as possible during the bonding process. this happens

according to the invention by a correct choice of the thermal resistances. By maximizing the thermal resistance Rth4, the heat flow from the lower substrate to the upper substrate is minimized, preferably even completely interrupted. Since a complete interruption of the heat flow, however, is virtually unattainable, it is almost always to a

Temperature change of the upper substrate come. The temperature difference ΔΤ is in particular less than 20 ° C, preferably less than 10 ° C, more preferably less than 5 ° C, most preferably less than 1 ° C, most preferably less than 0.1 ° C.

On the other hand, in particular, the temperature of the lower substrate should preferably be able to be set exactly by a heater in the lower substrate holder. In particular, the temperature of the lower substrate should correspond to the temperature of the lower substrate holder. The lower substrate holder becomes in particular to temperatures below 100 ° C., preferably below 75 ° C., more preferably below 50 ° C., most preferably below 30 ° C.

Furthermore, in particular, the temperature of the upper substrate of

Temperature of the cooling fluid and / or the heat conduction body correspond. In a very particular embodiment of the invention corresponds to the

Temperature of the cooling fluid, especially the ambient temperature. This is

especially the case when the atmosphere itself is used as the cooling fluid. The cooling fluid is in particular at temperatures below 100 ° C,

preferably below 75 ° C, more preferably below 50 ° C, most preferably below 30 ° C. In a very particular embodiment of the invention, the ambient atmosphere is used as a cooling fluid and has it

Room temperature or ambient temperature.

The diameters of the substrates can not be changed. The

Thermal conductivities and thicknesses of the substrates used are usually likewise predetermined by production conditions and can therefore usually not be used for the optimization according to the invention. The correct choice of the thermal resistances according to the invention preferably minimizes the heat flow, in particular from the lower substrate to the upper substrate, and maximizes the heat flow from the upper substrate to the cooling fluid. Thus, the temperature difference AT remains constant according to the invention.

A further aim of the choice of the thermal resistors according to the invention is, in particular, to keep the temperature of the upper substrate constant, in particular at ambient temperature, and therefore the

To minimize interference from other heat sources, in particular the heat source of the lower substrate. At a constant temperature of the lower substrate holder, and thus of the lower substrate, this is equivalent to maintaining the temperature difference ΔΤ between the upper and the lower substrate, in particular during the bonding process in the temperature range d. This is done primarily by maximizing the thermal resistance Rth4 between the substrates. By contrast, the temperature Tlu of the lower substrate should be able to be regulated as efficiently as possible by means of a heating device. The temperature of the lower substrate holder is designated Tp.

Preferably, the temperature Tp of the lower substrate holder is about each

Time identical to the temperature Tlu of the lower substrate. The

Forwarding the heat from the heater to the lower substrate is done mainly by minimizing the thermal resistances Rthl and Rth2.

processes

The method according to the invention or the processes according to the invention can be described on the basis of so-called temperature-time diagrams. In the temperature-time diagrams in particular a temperature, in particular the temperature T on, with the substrate holder according to the invention fixed substrate as a function of time t is shown (temperature graph). The temperature is displayed on the ordinate at the left edge of the temperature-time diagram. In the temperature-time diagrams also a distance-time curve can be represented (distance graph), at which one can read, how large to one

Time of the distance between the two substrates to each other. In this case, the ordinate of the distance-time curve is displayed on the right edge of the temperature-time diagram. Since the distance-time curve indicates distances from the mm to the nm range, it is preferably scaled in an integral manner. For the sake of clarity, however, the distance-time curve in the figures is shown with a linear scaling. For the sake of simplicity, only a temperature-time diagram or shorter, a Tt diagram, will be discussed below. In addition to the Tt diagram for the fixed substrate, a Tt diagram for the substrate holder according to the invention could also be described. However, the two Tt diagrams differ only marginally, especially in Reference to minimum deviations along the temperature axis, from each other. In the further course of the patent Tt diagrams are therefore synonymous with temperature-time diagrams of the fixed substrate and / or the

Inventive substrate holder used. This assumption is justified especially when the thermal resistances Rth2 and Rth6 are minimal. In this case, the thermal coupling between the substrate holder and the substrate is so good that one can assume that their temperatures are more or less identical.

Each diagram can generally be divided into six sections, in particular

Time periods are divided.

In the first, initial, section a, the substrate is approached from a relatively large distance. The distance between the two substrates in section a is greater than 1 mm, preferably greater than 2 mm, more preferably greater than 3 mm, most preferably greater than 10 mm, most preferably greater than 20 mm. A movement of the substrate within the section a does not lead to an increase in temperature by the other, in particular lower, second, substrate or the other, in particular lower, second, substrate holder, which can generally be heated to a temperature above room temperature. If the distance between the two substrates is reduced to such an extent that an influence by heat radiation of the second, lower substrate or the second, lower substrate holder and / or the heat convection of the surrounding gas takes place at the upper, first, substrate, a moderate occurs

Temperature increase at the top, first, substrate.

This range b of moderate temperature rise is called

Coarse approach area. The distance between the two substrates is between 10 mm and 0 mm, preferably between 5 mm and 0 mm more preferably between 1 mm and 0 μιη, most preferably between 100 μηι and 0 μιη.

If the substrates continue to approach each other, it comes at the end of the

Grobääherungsbereiches b to a sudden increase in the temperature of the upper, first substrate. There is a kind of heat coupling between both substrates. The heat leads to heating of the upper, first, substrate due to the small distance diameter ratio of substrate distance to substrate diameter. The ambient gases heated by thermal radiation can no longer diffuse fast enough from the gap between the two substrates and therefore preferentially transfer the heat directly from the lower, second, substrate to the upper, first, substrate. Similar considerations apply to the heat radiation, which has practically only the possibility to reach the surface of the upper, first, substrate. This area of strong heating of the substrate is referred to as the near approach area c. The distance between the two substrates is here between 1 mm and 0 mm, preferably between 100 μπι and 0 μπι, more preferably between 10 μηι and 0 μπι, most preferably between 1 μπι and 0 μιη.

The transition of the temperature profile from the Nahannäherungsbereich c in a so-called temperature saturation region d is preferably carried out by a mathematically continuous as possible but not differentiable transition. It is also conceivable that the transition takes place continuously, so that a separation of the areas c and d can no longer be made clearly. The shape of the temperature-time graph looks like a "shark's fin." However, other forms would also be conceivable.

In the temperature saturation region d, the bonding process according to the invention preferably takes place. The translational approach of the substrates is stopped, that is, the distance between the substrates remains constant. At this time For example, the upper, first substrate has a constant temperature T4o for a well-defined period of time tl, which corresponds to the length of the temperature saturation region d. With constant temperature T4o is a maximum temperature fluctuation of a maximum of 4 K, preferably a maximum of 3 K, more preferably a maximum of 2, on

most preferably at most 1K, most preferably at most 0.1K. The distance between the two substrates is constant in this range and is between 1 mm and 0 mm, preferably between 100 μπι and 0 μηι, more preferably between 10 μηι and 0 μηι, most preferably between 1 μιη and 0 μιη, in specific embodiments of the invention would be a further approximation of the two substrates in the area d also still possible. However, it must be ensured that there is still enough time left for the actual bonding process. Furthermore, in the temperature saturation region d, the temperature difference ΔΤ between the lower and the upper substrate remains constant. The fluctuations in the temperature difference ΔΤ are less than 4 K, preferably less than 3 K, more preferably less than 2 K, most preferably less than 1 K, on

most preferably less than 0.1 K. The temperature difference ΔΤ can

in particular by the choice of the thermal resistances and / or the

Heat sources, in particular the heater in the lower substrate holder, and / or the heat sinks, in particular the ühlfluid, be set exactly and reproducibly.

In particular, it is provided that the time interval t1, during which the constant temperature T4o sets at a constant distance d3, is more than 5

Seconds, preferably more than 10 seconds, more preferably more than 15

Seconds, more preferably more than 20 seconds, most preferably more than 40 seconds. This advantageously remains sufficient time for the bonding process.

Furthermore, it is provided in particular that the time interval t1, the distance d3 and / or the constant temperature T4o are determined before the first step, in particular empirically, preferably taking into account the temperature of the second substrate, the materials of the substrate holder, the heat conduction body and / or the substrates and / or the approach speed. Thus, it is particularly advantageously possible to set or calibrate the method before the first step such that the optimal parameters of the method can be determined.

The bonding process, in particular the fusion bond process, requires a time span t2 which is, in particular, less than or equal to the time interval t1. It is an important aspect of the invention that the bonding process preferably takes place within the period of the temperature saturation region d at the given temperature T4o. This has the advantage that the bonding process can take place without the temperature of the first substrate changing, as a result of which the run-out errors described above can be avoided, at least reduced.

In the subsequent cooling region e, the upper, first, substrate, in particular exponentieli, cools off.

In the following area f finally enters a constant saturation temperature, which is higher than the starting temperature of the upper, first, substrate in the first section a before the approaching process. However, it is generally lower than the temperature of the lower, second, substrate or

Substrate holder. It would also be conceivable to carry out a bonding process in the region f at the temperature T6o.

Preferably, before the application of the method according to the invention, all necessary physical parameters are determined which make it possible to obtain an exact statement about the temperature-time graph. The method according to the invention must be modified by varying the physical parameters be until it was ensured that during the actual bonding process precisely that temperature-time profile is formed, which is an optimal connection of both

Substrates allowed each other and above all to a corresponding one

Throughput leads. By the use of a corresponding inventive heat conduction body with appropriate thermal mass, the correct cooling fluid, the correct cooling fluid pressure, the correct

Cooling fluid flow rate, a correct approach profile, etc., the saturation temperature T4o in the area d, the time t of the area d and all other desired areas of the temperature-time graph

be adjusted accordingly.

Once the system is calibrated for temperature-time behavior, it is also ensured that the top, first, substrate has a well-defined temperature at a well-defined time, and that from the beginning of reaching that temperature, a well-defined time exists to complete the actual bonding process can be done by a deflection and / or solution of, in particular caused by vacuum, fixation. Being able to bond early in the area d results in two fundamentally important ones

Aspects of the invention. First, bonding can begin early, resulting in an immense increase in throughput, and second, it ensures that the substrate is extremely stable within a well-defined period of time

has constant temperature. This makes it possible according to the invention to completely avoid the run-out problems which are well known in the prior art. It is ensured that both substrates have a practically constant temperature during the time interval of the region d and practically do not change their temperature during the bonding process. It should again be explicitly mentioned in this context that the above circumstance of constant temperature does not mean that both substrates must have the same temperature. It may well be desirable to deliberately heat or cool at least one of the two substrates to a higher or lower temperature in order to pass through one Forced, forced thermal expansion to set a desired, forced substrate size, which leads to a congruence of the two functional units of both substrates. However, it is according to the invention to keep these once set temperatures constant during the bonding process.

In each method according to the invention described, the substrates can be pre-treated and / or post-treated. As a pre-treatment are especially in question

• Cleaning, especially by

o Chemical processes, in particular by

* Liquids, especially through

• Water

o Physical processes, in particular through

"Sputtering, especially through

• ions, in particular by

o Plasma activation

• Uncharged particles

• Grind

• polishing

• Aligning, in particular

o Mechanical alignment and / or

o Optical alignment

• deposits

As post-treatments are eligible

• Cleaning, especially by

o Chemical processes, in particular by

"Liquids, especially by

• Water

o Physical processes, in particular through ^■ sputtering, especially through

• ions

• Uncharged particles

• Grind

• polishing

• investigations, in particular

o Of the bond interface, in particular

^■ on defects (voids)

^» On registration errors, in particular

• run-out errors

• heat treatments, in particular

o In an oven

o a heating plate

• Renewed separation of the substrates, in particular by the method of WO2013 / 091714A1

The embodiment according to the invention makes it possible, above all, to compensate for the run-out error known in the prior art. Around

In order to ensure that the alignment accuracy has been minimized far enough, it is therefore particularly important to investigate the bond interface after bonding both substrates in order, if appropriate, to separate the substrates again by a special method, in particular the method from the document WO2013 / 091714A1 , Thus, a loss of both substrates, or the entire substrate stack, avoided and the substrates can, if necessary, be re-aligned and bonded.

The alignment accuracy that can be achieved by the system according to the invention or the process according to the invention is better than 100 μιη, preferably better than 10 μιη, more preferably better than 500 nm, on

most preferably better than 200 nm, most preferably better than 100 nm Alignment accuracy is particularly equal at each position of the

Substrate stack, which is a crucial and characteristic feature of a successful run-out error compensation. The standard deviation of alignment accuracy obtained by averaging all registration errors of the

Substrate stack is determined is less than 1 μπι, preferably less than 500 nm, more preferably less than 250 nm, most preferably less than 100 nm, most preferably less than 50 nm.

After the bonding process of the present invention and an optional but preferred positive test, the substrates are heat treated if necessary. The heat treatment is necessary in particular for fusion-bonded substrates. The heat treatment in this case leads to the generation of a permanent bond of both substrates, which can no longer be dissolved. If heat treatments of the substrates after the bonding process according to the invention are no longer necessary, it is dispensed with accordingly.

In a method according to the invention, the bonding of the two substrates takes place in the region d by the deformation of one, in particular of the upper, first, substrate. The deformation is preferably carried out centrally by the deformation element already described. The advantage of the first process according to the invention is above all in throughput. Since the bonding process already takes place in the section d and does not have to wait for the cooling of the upper, first substrate, the throughput (therefore the number of substrates that can be processed per unit of time with the embodiment according to the invention) can be increased in contrast to the prior art become. The cooling of the, upper, first,

Substrate is the adaptation process to the ambient temperature, which is predefined primarily by the surrounding atmosphere and / or the lower, second, substrate or the lower second substrate stringer. In another process according to the invention, the bonding of the two substrates in the region f is effected by the deformation of one, in particular of the upper, first, substrate. The deformation is preferably carried out centrally by the deformation element already described.

The temperatures T4o, T6o can be varied and optimally adapted by the substrate holder according to the invention, in particular by the thermal mass, the cooling elements and devices, the cooling processes, the cooling fluids, etc.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The show in:

Figure 1 is a not to scale, schematic cross-sectional view

a first embodiment of the invention a

Substrate holder,

Figure 2 is a not to scale, schematic cross-sectional view

a second embodiment of the invention,

Figure 3 is a not to scale, schematic cross-sectional view

a third embodiment according to the invention,

Figure 4 is not to scale, Scheraatische cross-sectional view

a fourth embodiment of the invention,

Figure 5 is a not to scale, schematic cross-sectional view

a fifth embodiment of the invention,

Figure 6a is a not to scale, schematic cross-sectional view

a first step of a method according to the invention, FIG. 6b is a schematic cross-sectional view, not to scale, of a second step,

FIG. 6c shows a schematic cross-sectional representation, not to scale, of a third step,

FIG. 6d shows a schematic cross-sectional representation, not to scale, of a fourth step,

FIG. 6e is a schematic cross-sectional view, not to scale, of a fifth step,

FIG. 6f shows a schematic cross-sectional representation, not to scale, of a sixth step,

Figure 7a is a schematic representation of a first temperature time and

Distance-time diagram,

Figure 7b is a schematic representation of a second temperature-time and

Distance-time diagram,

Figure 8 is a schematic representation of possible overlay errors and

Figure 9 is a schematic representation of a thermal equivalent circuit diagram.

In the figures, the same components or components with the same function with the same reference numerals. FIG. 1 shows a first embodiment of the invention

Substrate holder 1, comprising a fixing part 4 and a heat conduction body 2. The fixing part 4 has fixing elements 5, in particular vacuum webs, more preferably individually controllable vacuum webs, by means of which a not shown first substrate 1 1 can be fixed to a fixing surface 4o. The heat-conducting body 2 preferably has a plurality of ribs 3, which can deliver heat to an unillustrated fluid via their rib surface 3o. The heat conduction body 2 is connected to the fixing element 4 via a

Interface 6 connected.

FIG. 2 shows a second, preferred embodiment according to the invention of a substrate holder according to the invention, comprising one

Heat conduction body 2 ', which also acts as a fixing part. In other words, the heat conduction body 2 'and the fixing part are in one piece, in contrast to the embodiment of FIG. formed integrally or integrally. Thereby there is no interface between the fixing part and the

Heat conduction body 2 ', so that there is advantageously no thermal barrier, which hinders the removal of heat from the first substrate 11, not shown, to the fins 3 flowing around the fluid, not shown.

FIG. 3 shows a third, more preferred, invention

Embodiment of a substrate holder according to the invention 1 ", which has a bore 7 in the heat conduction body 2". The bore 7 allows the access of a deformation element 8, in particular of a mandrel, to the rear side 1 lo of a substrate 1, not shown. Otherwise, this embodiment corresponds to that of FIG. 2, so that reference is made to the description of this figure.

FIG. 4 shows a fourth embodiment of the invention

Inventive substrate holder 1 "', in addition to those mentioned in Figure 3 Features still on recesses 9 in the fixing surface 4o has to minimize the contact between the not shown back of the first substrate 1, not shown. This minimization serves to avoid, in particular metallic, contamination of the substrate by the fixing surface 4o. Furthermore, it serves to avoid local deformation of the substrate by particles. To increase the heat coupling, the recesses 9 can be flooded with fluids of high heat capacity and / or thermal conductivity.

FIG. 5 shows a fifth embodiment of the invention

Inventive substrate holder 1, which in addition to the features mentioned in Figure 3 via recesses 9, which are filled with knobs and / or needles and / or pedestals 10, has the contact between the not

shown back of the first substrate 1 1 ', not shown, and to minimize a largely full-scale support of the first substrate 1 to 1

guarantee. This minimization also serves to avoid,

especially metallic, contamination. The depressions 9 can for

Increase the heat coupling with fluids of high heat capacity and / or thermal conductivity are flooded.

FIG. 6 a shows a first step of an exemplary method according to the invention, wherein initially a first, upper substrate 1 1 is located at a distance d 1 from a second, lower substrate 1 1 '. This process step takes place in previously defined area a of the associated T-t diagram. The substrates 1 1, 1 1 'approach each other, wherein the thermal influence of the upper, first substrate 11 by the lower, second substrate 1 1' and a lower substrate holder 14 due to the relatively large distance, as already described above, as far as possible is excluded.

In a subsequent step, the approach of the two substrates 1 1, 11 'to each other to a distance d2. The system is located to this Time in previously defined area b, the so-called

Grobannäherungsbereich in which already a relatively small heating of the upper, first substrate 1 1, in particular by the heat radiation of the lower substrate 1 Γ, takes place.

In a subsequent step, the further approach of the two substrates 1 1, 1 1 'to each other takes place on one, as already described above

well-defined, distance d3. The system is at this time in previously defined area c, the so-called Nahannäherungsbereich in which a sudden warming of the upper, first substrate 1 1, in particular by heat radiation and Wärmekonvektion occurs.

In a subsequent step according to FIG. 6d, the bonding process of the two substrates 11, 11 'takes place. The substrates 1 1, 1 1 'are constantly at a distance d3. The substrates 1 1, 1 1 'are at this time in the previously defined area d, the so-called bonding area, in which the temperature T4o is constant for a time tl.

In a subsequent step according to FIG. 6e, the cooling of the substrates 11 and / or 11 'takes place in the previously defined region e. The cooling is again an adaptation process of the temperature of the upper, first substrate 1 1 to the ambient temperature, in particular the temperature of the surrounding atmosphere, and / or the lower, second substrate 11 'or lower

Substrate holder 14. At this time, but already the connection of the two substrates 1 1, 1 Γ, in particular by a pre-bond.

On the representation of the previously defined area f by a further figure is omitted because it can not gain any significant knowledge. As already disclosed in the description text, the

Bonding also be done in the constant temperature range in the range f. FIG. 7 a shows a previously described temperature-time diagram, with the previously defined six characteristic temperature ranges a, b, c, d, e, f, which are indicated on the upper horizontal axis. On the lower horizontal axis, the time t is given in seconds, on the left

vertical axis, the temperature T is plotted in Kelvin. On the right vertical axis is the unscaled (a.u.) distance d between the two

Substrates 1 1 and 11 'applied. Furthermore, four temperature graphs 12, 12 ', 12 "and 12"' are shown. The temperature graph 12 represents the temperature of the first substrate 11. The temperature graph 12 'represents the temperature of the heat conduction body 2, 2', 2 ", 2"', 2 ^IV more or less coincident with the temperature Tk of the cooling fluid. Prior to the approach of the two substrates 11, 1 1 'together, it also corresponds approximately to the temperature Tl o of the upper substrate 1 1. The temperature graph 12 "represents the temperature of the second substrate 1 1'. The temperature graph 12"'represents the temperature of If the thermal coupling between the second substrate 1 1 'and the lower substrate holder 14 is large enough, these two temperatures are almost identical.

In addition, a distance graph 13 is given, which indicates the distance d between the two substrates 1 1 and 1 Γ. The distance graph 13 is to be interpreted exclusively symbolically and will in reality indicate a gentler transition from the region c into the region d, since the substrates j a are negative

accelerated, so slowed down, must be. In particular, the substrates can change their speed even in the approach phase. The

Temperature difference ΔΤ between the temperature of the lower substrate and the temperature of the upper substrate in the temperature saturation region d can by the thermal resistors and / or the heat source, in particular a heater in the lower sample holder 14, and / or a heat sink, in particular the

Cooling fluid to be set accurately and reproducibly. The courses of the temperature graph 12 and the distance graph 13 during an exemplary method according to the invention are as follows: At the beginning of the method, ie on the far left on the time scale in the one with a

marked area (so-called temperature range a), the two substrates 1 1, 1 1 'approached each other, so that the distance d between the substrates 1 1, 1 1' is reduced. At the beginning of the process, the distance between the two substrates 1 1, 1 1 'dl, which is successively reduced. In temperature range a, the temperature of the first or upper substrate 1 1 is practically constant T l o.

The temperature range a is followed by the temperature range b, in terms of time, in which the temperature of the substrate 1 1 rises relatively low

(Temperature curve section T2o), while the distance d between the substrates 1 1, 1 1 'is further reduced.

The temperature range b is followed by the temperature range c, in which the temperature of the substrate 1 1 increases relatively sharply compared to the temperature range b (temperature curve section T3o), while the distance d between the substrates 11, 11 'is further reduced. At the end of

Temperature range c is the final practically constant distance d between the substrates 1 1, 1 1 'reached.

The temperature range c is followed by the temperature range d, in which the distance d remains constant and the temperature T4o of the first substrate 11 is practically constant. The same applies to the temperature difference ΔΤ between the lower substrate 1 1 'and the upper substrate 1 1. This constant temperature T4o is maintained for a period tl. In particular, it should be noted that the transition from the temperature range c (so-called Nahekäherungsbereich c) in the

Temperature range d (so-called bond area d) takes place abruptly. The temperature range d is followed by the temperature range e, in which the temperature of the substrate 1 1 drops (temperature curve section T5o), while the distance d remains practically constant. In the following temperature range f is practically constant temperature of the substrate 1 1 before (see

Temperature curve section T6o).

FIG. 7b shows another temperature-time diagram, with the previously defined six characteristic temperature ranges a, b, c \ d \ e, f. The distance graph 13 is identical to that of FIG. 7a. The temperature graph 12 corresponds to that of FIG. 7a in the temperature ranges a, b, c, f, so that reference is made to the explanations for FIG. 7a for these ranges. The difference from FIG. 7a is found in the regions c 'and d' in comparison to the regions c and d in FIG. 7a. In this example, the transition from the near approach region c 'into the bond region d' does not occur abruptly as in FIG. 7a but continuously.

FIG. 8 shows several in the diagrams I to VII, already above

addressed or defined, possible overlay errors between upper

Structures 15 of a top substrate 11 and bottom structures 15 'of a lower substrate 1 1', at least some of which can be avoided with the invention. Some of the overlay errors are known under the name run-out error.

In the overlay error of FIG. 8-1. it is not one

congruent overlap of an upper structure 15 and a lower structure 15 'as a typical result of a run-out error. The structures 15, 15 'are indeed shape but not congruent. The cause of such an error is (i) a fundamentally incorrect production of the structures 15, 15 'on the substrates 11, 11' and / or (ii) a distortion of the structures 15, 15 ', in particular due to a distortion of the substrates 1 1, 1 1 ', before bonding and / or (iü) distortion the structures 15, 15 ', in particular by a distortion of the substrates 11, 1 1', during bonding. Another possibility is a global one

Displacement, the two substrates 1 1, 1 1 'to each other. In this case, however, there would be a fundamental orientation problem of the global orientation of two substrates to each other, which is rarely associated with the term run-out.

Figs. 8-Π. shows another overlay error of two mutually rotated structures 15 and 15 ^* . The rotation of the two structures 15 and 15 'to each other is exaggerated and makes in reality only a few degrees, in particular only a few tenths of a degree. It occurs when the two structures 15, 15 'are either (i) improperly formed on the two substrates 11 and 11' and / or (ii) before the bonding operation, in particular local distortion in the vicinity of Structures 15, 15 'comes, which leads to a corresponding, in particular local, rotation of the two structures 15, 15' to one another and / or (iii) during the bonding process to a, in particular local distortion in the vicinity of the structures 15, 15 ' comes, which leads to a corresponding, in particular local, rotation of the two structures 15, 15 'to each other. Another possibility is in a global one

Rotation of the two substrates 1 1, 1 1 'to each other. In this case, an overlay error of type 8-II would have to be at multiple positions between the two

Substrates 1 1, 1 1 ', in particular radially from inside to outside increasingly be recognizable.

The overlay errors according to the figures 8-III. to 8-VII. are predominant

Scaling errors caused by (i) incorrect production and / or (ii) distortion of the structures 15, 15 ', in particular by distortion of the substrates 11, 11' before bonding and / or (ii) distortion of the structures 15, 15 ', in particular by a distortion of the substrates 1 1, 1 1' arise during bonding. They are typically not referred to as run-out errors. FIG. 9 shows a schematic, not to scale, sectional partial view of a substrate holder according to the invention with an equivalent circuit diagram of the thermal resistances Rth1 to Rth8 as described above.

The thermal resistances Rth1 to Rth3 should be minimal in order to allow a maximum heat conduction from the lower substrate holder 14, which in particular has a heating device (not shown), to the lower substrate 11 '. As a result, according to the invention an efficient and fast

Heating of the lower substrate 1 1 'allows. Furthermore, a chain of minimum thermal resistances can very quickly change the

Temperature T lu of the lower substrate 1 1 'be accomplished.

The thermal resistance Rth4 should according to the invention a maximum s. In the, purely theoretical, ideal case of an infinitely large thermal resistance Rth4, no amount of heat would pass from the lower substrate 11 'to the upper substrate 11. Due to the finiteness of the thermal resistance Rth4 always a non-vanishingly small amount of heat from the lower substrate 1 1 'reaches the upper substrate 1 1. By the choice of a vacuum or a special

Gas mixture between the two substrates 1 1 and 1 1 ', the thermal resistance Rth4 can be adjusted relatively easily and accurately.

In accordance with the invention, the thermal resistances Rth5 to Rth8 should again be minimal in order to allow the maximum possible and therefore efficient heat conduction between the cooling fluid, in particular the atmosphere, and the upper substrate 11. Of inventive and crucial importance is the correct, targeted and repeatable setting of an upper temperature T4o and the temperature difference ΔΤ between the temperature T4o of the upper

Substrate 1 1 and the temperature Tlu of the lower substrate 1 1 'during the bonding process in the temperature saturation region d. This is inventively especially by (i) the targeted selection of at least one of the thermal Resistors Rthl to Rth8 and / or (ii) the setting of the lower temperature Tlu ~ Tp, in particular by a heater in the lower substrate holder 14 and / or (iii) the setting of the upper temperature Tl o -Tk, in particular by the ühlfluid invention.

D esigne s te rs

substrate holder

Heat conduction body

ribs

rib surface

fixing

fusing

fixing

interface

drilling

flexure

Recess / exception / recruiting

Knobs / needles

substratum

temperature graph

distance graph

Lower substrate holder

structure

substrate distance

Period of time

Temperature / temperature curve sections Temperature / temperature curve sections Temperature Substrate holder

Temperature of the heat conduction body Temperature of the cooling fluid

temperature ranges

Claims

Godfather sayings

Substrate holder (1, 1', 1", ", 1 ), having a fixing surface (4o) for holding a substrate (11, 1Γ), characterized in that the substrate holder (1, Γ, l'\ 1 "', 1 ^ϊν ) has a heat conduction body (2, V, 2", 2'", 2 ^,v ) for dissipating heat away from the fixing surface (4o).

Substrate holder (1, 1 ', 1", 1'", 1 ^ϊν ) according to claim 1, characterized

characterized in that the heat conduction body (2, 2', 2", 2"',

2 ^!V ), in particular on its side facing away from the fixing surface (4o), has ribs (3) for dissipating the heat.

Substrate holder (1, 1', 1", 1'", 1 ^1V ) according to claim 2, characterized

marked that the ribs

(3) are arranged perpendicular to the fixing surface (4o) and/or parallel to one another.

4. Substrate holder (1, 1', 1", 1"\1 ^IV ) according to one of the preceding claims, characterized in that the heat conduction body (2, 2', 2", 2"', 2) is also used to supply heat to the fixing surface (4o) is formed.

5. Substrate holder (1, 1% 1", 1 "', 1 ^1V ) according to one of the previous ones

Claims, characterized in that the fixing surface (4o) is formed in one piece with the heat conduction body (2, 2', 2", 2"\ 2 ^IV ).

6. Substrate holder (1, 1 ', 1", 1 ^** ', 1 ^IV ) according to one of the previous ones

Claims, characterized in that the substrate holder (1, 1', 1", 1"', 1 ^IV ) has a deformation element (8) for deforming the substrate (11, 11').

7. Substrate holder (1, 1 ', 1", 1'", l ^iV ) according to claim 6, characterized

characterized in that the deformation element (8) is arranged centrally in the substrate holder (1, Γ, 1", 1'", 1 ^IV ).

8. Substrate holder (1, 1', 1", 1"', l ^{, v} ) according to claim 6 or claim 7,

characterized in that the deformation element (8) is such

is designed so that the substrate (11, 11') can be deformed away from the fixing surface (4o).

9. Substrate holder (1, Γ, 1", 1"', l ^iV ) according to one of the previous ones

Claims, characterized in that in, on and/or on the

Fixing surface (4o) fixing elements (5) for fixing the substrate (11, 11 ') are arranged.

10. Substrate holder (1, Γ, Γ ', 1"\ 1 ^IV ) according to claim 9, characterized

characterized in that the fixing elements (5) are at least partially

Vacuum railways are.

11. Substrate holder (1, 1\1", ", l ^,v ) according to one of the previous ones

Claims, characterized in that the specific heat capacity of the heat conduction body (2, 2\ 2'\ 2'", 2 ^!V ) is greater than 0.1 kJ/(kg*K), preferably greater than 0.5 kJ/(kg*K) , more preferably greater than 1 kJ/(kg*), most preferably greater than 10 kJ/(kg*K), on

most preferably greater than 20 kJ/(kg*K).

12. System for bonding a first substrate (11) to a second substrate (11'), comprising at least one, in particular upper, substrate holder (1, 1', 1", 1"', 1 ^IV ) according to one of the preceding claims Holder of at least one of the two substrates (11, II ⁴ ).

13. Use of a substrate holder (1, 1', 1", 1"', 1 ^IV ) according to one of

Claims 1 to 11 as an upper substrate holder (1, 1 ', 1", 1"', 1 ^IV ).

14. Method for bonding a first substrate (11) to a second

Substrate (11'), the substrates (11, Π') being brought closer together in a first step, so that the temperature (T2o, T3o) of the first substrate (11) increases, the substrates (11) being brought closer together in a second step ( 11, 11') stopped and a distance (d3) between the

Substrates (11, 11 ') is kept constant in such a way that at a constant distance (d3) a constant temperature (T4o) of the first substrate (11) is established for at least a period of time (tl), in a third step within the period of time (tl). tl) at a constant temperature (T4o) of the first substrate (11), the two substrates (11, 1 Γ), at least temporarily,

be connected to each other.

15. The method according to claim 14, characterized in that the distance (d3) at which the constant temperature (T4o) is established over the period of time (tl) is between 1 mm and 0 mm, preferably between 100 μπι and 0 μπι, still more preferably between 10 μm and 0 μm, most preferably between 1 μm and 0 μm.

16. The method according to any one of claims 14 to 15, characterized in that the period of time (tl) during which the constant temperature (T4o) is established at a constant distance (d3) is more than 5 seconds, preferably more than 10 seconds preferably more than 15 seconds, even more preferably more than 20 seconds, most preferably more than 25 seconds.

17. The method according to any one of claims 14 to 16, characterized in that the time period (tl), the distance (d3) and / or the constant

Temperature (T4o) can be determined before the first step, in particular empirically, preferably taking into account the temperature of the second substrate (IT), the materials of the substrate holder (14, 1, Γ, 1", Γ ^* \ 1 ^IV ), the heat conduction body ( 2, 2', 2", 2'", 2 ^JV ) and/or the substrates (11, 11') and/or the approach speed.

18. Product, in particular substrate stack, comprising a first substrate (11) and a second substrate (11'), the substrates (11, 11') being bonded to one another using a method according to one of claims 14 to 17.

19. Using a substrate holder (1, 1', 1", 1"\l ^,v ) according to one of the

Claims 1 to 11, for holding a substrate (11, 11') during a method according to claims 14 to 17.